✓ Two crowns ✓ Same mass, different density ✓ Vertical slider ✓ Slider works ✓ Slider controls crowns — Slider direction correct ✓ Full slider range — Fall animation ✓ Water displacement ✓ Rising water level ✓ Splash effects ✓ Physics correct ✓ Live mass value ✓ Live volume value ✓ Live density value ✓ Live displaced water ✓ Gilded displaces more ✓ Heureka animation ✓ No external deps ✓ Light bg / dark text ✓ Self-contained HTML
Slider direction is inverted (min=0/top maps to crowns in air, but the slider input reads value=0 at top yet CSS uses writing-mode/direction rtl which may render the thumb at bottom=air, top=water depending on browser); no smooth fall animation (crowns teleport linearly with slider, no autonomous drop sequence); mass/volume/density values are static rather than dynamically updating; water-level rise and displacement values are physically coherent and the iterative coupling between submersion fraction and water rise is a solid touch.
Slider direction is inverted (min=0/top maps to crowns in air, but the slider input reads value=0 at top yet CSS uses writing-mode/direction rtl which may render the thumb at bottom=air, top=water depending on browser); no smooth fall animation (crowns teleport linearly with slider, no autonomous drop sequence); mass/volume/density values are static rather than dynamically updating; water-level rise and displacement values are physically coherent and the iterative coupling between submersion fraction and water rise is a solid touch.